It is known that molded case circuit breakers (MCCB) are mounted into electric control cabinets by attaching the MCCB to a bus bar that is fixed within an interior of the electric control cabinet, e.g. at a back wall of the electric control cabinet. For securing the MCCB at the bus bar, often fixation screws are used, since they provide a secure fixation of the MCCB at the bus bar and are easy to remove in case the MCCB is broken and has to be replaced.
For many applications and due to cost efficiency reasons, electric control cabinet space is rare. Therefore, MCCBs with small outer dimensions and compact connection devices have been developed. For saving space, screw holes for fixation screws have been moved from a side to an inside of the MCCBs. Standard MCCBs have a plurality of screw holes, especially three, aligned side by side for fixing the MCCBs to the bus bar. However, for a fixation procedure it is hard to locate all screws at a correct place at the MCCB or keeping them in position before screwing them into the bus bar. Since the screw hole is inside the MCCB, it is hardly possible and sometimes even impossible to hold the screws with external screw holding device, such as forceps, in position. As a result, e.g. during positioning the screws at the MCCB, one or more screws can fall off the MCCB and fall into the electric control cabinet. These screws may even block subsequent assembly at the bus bar. In that case, the screw must be removed and a new screw has to be located at the MCCB. This overall procedure is quite time and cost intensive.